Medically reviewed by Dr. A.M. van Coevorden, dermatologist
A cold sore is a herpes infection on the lips or around the mouth, caused by the herpes simplex virus (HSV). You get small, painful blisters that dry into crusts. The virus is common. There are two types: type 1 is usually on the lips and face, type 2 usually around the genitals. In principle both types can cause symptoms anywhere on the skin and adjoining mucous membranes.
Infection happens mainly through direct contact with the virus, which enters the body through the skin and mucous membranes. You can get it through kissing, sexual contact, or by touching the spots with your fingers, which can move the virus to another place. You can also be infected via objects such as towels. Outside the body the virus only survives a short time.
The first infection is called a primary infection and usually happens in childhood, often without you noticing. In about 10% mild symptoms develop: children can become ill, get a fever and have inflamed skin, while adults can have a sore throat and swollen glands around the area. The skin often feels burning or painful. On average it takes 3 to 9 days before the symptoms are visible.
Once you are infected, the virus stays in your body for the rest of your life. It withdraws into nerve cells in the skin and is then inactive: this is called being latent. The virus can become active again when your resistance is lowered or through triggers such as fever, sunlight (high in the mountains on a winter-sports holiday, a sunny holiday or a tanning bed), menstruation and stress.
A cold sore is usually on the lips or around the mouth. Often the skin feels burning or painful first, then small blisters appear that feel painful, and these dry into crusts that fall off after a while. The degree of symptoms varies: usually it is mainly cosmetic, but some people have a lot of pain or a swollen lip. One person has it only a few times in their life, another very often.
Through intensive skin contact you can also get herpes in other places, such as the buttocks or fingers, or around the genitals. If you have (atopic) eczema, the herpes can spread across large areas of the skin, often with a fever and feeling unwell. In that case, contact your doctor straight away.
Please note
Is the herpes near your eye, with a red eye, watering, poor tolerance of daylight or blurred vision? Then always contact your doctor straight away. This can cause permanent damage to your sight and sometimes needs urgent care.
Yes. An active cold sore is very contagious, especially the fluid in the blisters. Do not touch the spots with your fingers, do not share towels, make-up, plates or cutlery, and avoid kissing and cuddling babies until the spots have healed.
Your doctor can usually tell from the blisters whether you have herpes. If there is doubt, further testing follows, usually a skin swab. If needed, antibodies against the herpes virus can be detected through a blood test.
There is no treatment that kills the herpes virus for good. There are medicines that reduce the pain and shorten how long the symptoms last. Antiviral creams are available at the chemist and pharmacy, but their effect is limited. Zinc ointment speeds up the drying of the blisters and you may apply it as often as you like. For pain you can take paracetamol at the standard dose.
For a severe infection your doctor can prescribe antiviral tablets. These work best if you start them within 72 hours of the first symptoms. The crusts eventually fall off on their own; a neutral cream makes them softer. Apply all creams carefully and only to the spot itself, preferably with a cotton bud or gauze, and wash your hands well afterwards.
An active herpes spot is very contagious. This is how you limit the spread:
Cover the spot with a plaster where possible. Do not touch the spots with your fingers and do not scratch the crusts. Apply ointment with a cotton bud rather than your fingers. Do not use lipstick with a cold sore, keep flannels and towels away from the spots, wash your hands right after touching them and do not rub your eyes.
Keep make-up, towels, plates, glasses and cutlery for yourself and wash them straight away. Avoid direct body contact and especially kissing or cuddling babies. With herpes around the genitals, avoid sexual contact until everything has healed; a condom does not give full protection.
Infection of a newborn can be serious and sometimes even fatal, because the immune system is not yet fully developed. It can also be dangerous for people with reduced immunity, for example from chemotherapy or immunosuppressant medication. It is better to postpone a visit until the infection has passed.
Tell your midwife or doctor if you or your partner have had herpes on the vagina, penis or anus. Sometimes a caesarean section is needed. Men with recurring herpes around the genitals should use a condom during sexual contact with their pregnant partner.
Anyone who has the herpes virus carries it for life. In some people it becomes active now and then, so the symptoms return. In a small group this happens so often and so severely that it really troubles them. Over time the symptoms usually become less severe. Until then, antiviral tablets can help, and sometimes the doctor prescribes a maintenance dose to prevent new outbreaks.
Yes, an active cold sore is very contagious, especially the fluid in the blisters. Do not touch the spots with your fingers, do not share towels or cutlery, and avoid kissing and cuddling babies until the spots have healed.
No. Anyone who has the virus carries it for life. It withdraws into the nerve cells and can become active again now and then. Over time the symptoms usually become less severe.
The virus can become active again when your resistance is lowered or through triggers such as fever, sunlight (mountains, sunny holidays, tanning beds), menstruation and stress.
Antiviral creams are available at the chemist and pharmacy, but their effect is limited. Zinc ointment speeds up the drying of the blisters. For a severe infection, antiviral tablets work best, started within 72 hours of the first symptoms.
No. Infection of a newborn can be serious and sometimes even fatal. Avoid kissing and cuddling babies in particular, and it is better to postpone a visit until the spots have healed.
Painful blisters on one side of the body, caused by the chickenpox virus.
A contagious viral infection with itchy blisters all over the body.
A highly contagious bacterial skin infection with honey-yellow crusts.
